Thiobenzene-diol-polyamine corrosion inhibiting composition



United States Patent O This invention relates to a novel corrosion inhibiting composition useful to inhibit corrosion of ferrous metals in aqueous systems and particularly in aqueous systems containing carbon dioxide which are used in the secondary recovery of crude oil from underground reservoirs by water flooding.

Techniques for the secondary recovery of crude oil from reservoirs which are depleted or partially depleted (insofar as primary recovery techniques are concerned) are becoming more important, and one method which is quite useful involves the pumping of water into the formation under pressure through input Wells to force the oil toward output wells from which the oil is recovered. This method is known as water flooding.

Carbon dioxide is sometimes added to the water used in these Water flooding methods as indicated in US. Patents Nos. 1,511,067, 1,658,305, and 2,875,833. The presence of carbon dioxide in the flooding Water causes a serious corrosion problem with respect to the metallic equipment used to pump the water into the formation, particularly when hot water is used.

The primary object of this invention is to provide a composition and method for inhibiting the corrosion of ferrous metals exposed to water containing carbon dioxide. Another object of the invention is to provide a method for inhibiting the corrosion of equipment and tubing used to inject water containing CO into oil formations.

Broadly stated, this invention comprises the composition formed by heating a mixture of thiobenzene (also called thiophenol and benzenethiol) and the dehydrationcondensation reaction product of an unsaturated diol and a polyalkylene polyamine, and the method of using the inhibitor to prevent corrosion of ferrous metals in an aqueous system containing carbon dioxide.

It is reasonable to assume that certain compounds will be discovered to be equivalent to thiobenzene for use in this invention, and it wi-ll be obvious to those skilled in the art to try substitutes such as toluenethiols; thiobenzene with an .alkyl or alkyl groups substituted on the benzene ring; thiobenzene with alkyl alcohol or alkyl alcohols substituted on the benzene ring; thiobenzene with alkyl amines or alkyl amines substituted on the benzene ring.

THE REACTION PRODUCT OF THE UNSATU- RATED DIOL AND POLYALKYLENE POLY- AMINE Suitable unsaturated diols include compounds of the formula wherein R is selected from the group consisting of hydrogen, methyl, and ethyl, and x is selected from the group consisting of CEC and CH=CH Specific diols include:

2-butynediol-1,4 l-methyl-Z-butynediol-1,4 1,4-dimethyl-2-butynediol-1,4 1,1-dimethyl-2-butynediol-l,4

1,1,4,4-tetramethyl-2-butynediol-1,4 1-ethyl-2-butynediol-1,4 1,4-diethyl-2butynediol-1,4 1,l-diethyl-Z-butynediol-1,4 1,1,4,4-tetraethyl-2-butynediol-1,4 1-methyl-1-ethyl-2-butynediol-l,4 1-methyl-4-ethyl-2-butynediol-1,4 1,1-dimethyl-4-ethyl-2-butynediol-1,4 l,1-diethyl-4-methyl-2-butynediol-1,4 1,4-diethyl-1-methyl-2-butynediol-l,4 1,1-dimethyl-4,4diethyl-2-butynediol-1,4 1,l,4-trirnethyl-2-butynediol-1,4

1, 1,4-triethyl-2-butynediol-1,4 1,4-dimethyl'1-ethyl-2-butynediol-l,4 1,1,4-trimethyl-4-ethyl-2-butynediol-1,4 1,4-dimethyl-1,4-diethyl-2-butynediol-l,4 l, 1,4-triethyl-4-methyl-2-butynediol-1,4

The butenediols corresponding to the above butynediols, as for example, 2-butenediol-l,4; 1,1-dimethyl 2 butenediol 1,4; 1,1,4,4-tetramethyl-2-butenediol 1,4; and 1,4-diethyl-1-methyl-2-butenediol-1,4 to name only a few, are also suitable for preparing the reaction products of this invention.

The butynediols are readily prepared by the condensation of acetylene with aldehydes or ketones in the presence of copper acetylide as taught by Reppe et al. in the United States Patents Nos. 2,232,867 and 2,300,969, while the butenediols may also be readily prepared by partial reduction of the corresponding butynediols by treatment of the butynecliol in aqueous alkali with electrolytic zinc in accordance with the United States Patent No. 2,267,- 749, issued to Reppe et al.

Suitable polyalkylene polyamines include compounds of the formula wherein R is a radical selected of ethylene and propylene and 4, inclusive.

Exemplary, but no limitative of the polyalkylene polyamines suitable for preparation of the reaction products of our invention, are diethylene triamine, triethylene tetramine, tetraethylene pentamine, pentaethylene hexylamine, dipropylene triamine, tripropylene tetramine, and tetrapropylene hexylamine.

In forming the dehydration-condensation reaction product of the unsaturated diol and the polyalkylene polyamine, it has been found to be necessary to carry out the reaction in the presence of a small amount of an ionizable compound of a chelate-forming metal. The chelate-forming metals are those metals other than the alkali, alkaline earth, and lanthanide metals. In general, the best chelateformers are cations of small size and high nuclear or ionic charges, such as the metals having atomic numbers of 24-30, 42-48, and 74-80, although We may employ metals selected from a somewhat broader group of metals including those having atomic numbers of 22-30, 41-48, 49-50, and 73-83, inclusive. As indicated above, We prefer to use a copper compound. Although chloride salts may be employed, we prefer to use other ionizable compounds such as metal acetates or other compounds of organic acids. A particularly suitable compound is copper acetate.

The amount of metallic compound depends somewhat upon the particular reactants and metal used; for eX- ample, titanium is more active than copper and therefore may be employed in smaller quantities. The amount of metal employed affects the rate of reaction, and since the reaction is exothermic, the desired amount will also depend upon the heat transfer characteristics of the equipmeat in which the reaction is carried out. It has been from the group consisting y is an integer from 1 to established, however, that in the case of copper the amount of metal should preferably not exceed about onehalf gram of metal ion per mole of the unsaturated diol. If this limit is exceeded, the reaction proceeds very rapidly and the resulting product generally contains an excess of a high molecular weight resinous fraction and therefore lacks certain desired physical characteristics such as viscosity and water solubility. We have also found that mere trace quantities of copper in the order of 5 parts of copper acetate per million parts of diol are effective to promote the desired reaction involving the splitting-off of water to form the condensation product. We generally use from about 5-100, and preferably from about -50 parts of copper acetate per million parts of diol. Example 1 illustrates a preferred amount of 50 parts of copper acetate per million parts of diol.

It may be that the unsaturated d-iol inherently contains a small amount of copper ion by way of impurity resulting from the use of copper acetylide as a catalyst during the preparation of the diol in accordance with the prior art as indicated above. In specifying that the reaction of the unsaturated diol and the polyalkylene polyamine should be carried out in the presence of a metallic ion, we are including the use of an impure diol as well as the affirmative addition of the metal compound as indicated above.

In carrying out the reaction in accordance with the best mode, the polyalkylene polyamine and the unsaturated diol are reacted in the presence of a small amount of a metal ion in accordance with the following general procedure. 7

The unsaturated diol and the polyalkylene polyamine may be simply mixed (preferably in equimolar quantities, but possibly from about /22 mole equivalents of amine per mole equivalent of the diol) and the metal compound added thereto. We prefer, however, to dissolve the metal compound in a small quantity of water, and then mix the solution with the diol prior to addition of the amine. The diol is preferably heated slightly to facilitate mixing of the metal compound therewith.

The mixture of diol, amine, and metal compound is then heated slightly to initiate the reaction, in a reaction vessel equipped for the azeotropic removal of water. When the reaction commences, the temperature begins to rise at an accelerated rate, and heating should be discontinued. The water which is formed is trapped and removed and, the temperature is allowed to rise slowly until the condensation of water has ceased. After the water of reaction has been removed, the mixture is allowed to cool, an azeotropic solvent such as benzene or toluene is added, and azeotropic distillation conducted to trap out residual water. The solvent is stripped from the mixture after which the then-existing temperature is preferably maintained for about 45 minutes or an hour to ensure completion of the reaction.

The weight ratio of thiobenzene to dehydration-condensation product may be varied between 1-to-5 and 5-to-1, although it is desirable to limit the ratio to from 1-to-2 to 2-to-l. We have found that a 1-to-1 composition is preferable. If too much thiobenzene is used, the mixture is too nearly water-insoluble to be of practical benefit. If more than 5-to-1 of the dehydration-condensation reaction product is used, the resulting composition will probably be too expensive to be of practical value.

The composition is formed by mixing the thiobenzene with the dehydration-condensation reaction product and heating the mixture to a temperature of about 40 C.- 140 C., preferably about 100 C.-130 C., for about 5-30 minutes and preferably 10-20 minutes.

It is not known whether the resulting composition is an adduct or a reaction product.

The amount of inhibitor composition used will depend upon the other elements in the flooding water and the temperature of the water. The particular water to be employed in the water flooding operation should be tested for corrosive properties with different concentrations of our inhibitor composition prior to field use thereof. We have found, however, that 5-25 parts per million of our composition are effective to provide over 60% Protection in a rather severe test as indicated in Example 11 below. It is important not to use more than about 25 parts per million of apparent thiobenzene in the aqueous system; for example, not more than about 50 parts per million of a l-to-l composition or about 30 parts of a 5-to-1 composition should be used. Exceeding these upper limits of thiobenzene is likely to accelerate rather than inhibit corrosion.

The following examples are set forth to illustrate the best mode of preparing and using the corrosion inhibiting composition of this invention, it being understood that they are not to be construed as limiting the scope of the invention.

Example 1 Into a 500 ml., S-necked, round bottom flask, place one mole (86 gm.) of 2-butyne-l,4-diol and 0.86 ml. of a stock solution of copper acetate. (This stock solution consists of 5 gm. of Cu(C H O H O dissolved in 1,000 ml. of de-ionized water heated to 50 C.) The temperature is raised to the melting point of the diol (575 8 C.), while stirring, to mix in the copper. To the warm solution add one mole of tetraethylene pentamine (189 grams) while continuing to stir the mixture. Raise the temperature to 180 C. and hold. Water begins to distill over at approximately 170 C. Continue distillation until 1820 ml. of distillate has been trap ed. Cool ingredients to 70 C. and add 30 ml. of toluene for azeotrope of remaining water. Raise the temperature. Azeotropic distillation begins at approximately 134 C. Trap and remove water only as thimble fills. The temperature will slowly rise with removal of residual water. As the temperature reaches 190 C., measure the water (it should be near 16 ml. volume). Continue to let the temperature rise as toluene is stripped free of the reaction product. The temperature should not be allowed to exceed about 225 C. A few ml. of a yellow distillate will be trapped out in the toluene at temperatures between 190225 C. The product forms a bright, clear solution in water.

One part by weight of the above reaction product is added to one part of thiobenzene and the mixture is heated to C. for 15 minutes and then diluted to 50% with ethanol.

Example 2 To 88 grams of 2-butene-1,4-diol, add 0.002 gram CuCl Using a standard reflux apparatus, weigh into the flask 189 grams of tetraethylene pentamine. Raise the temperature to about C., hold for about one hour, and then allow to cool. Add 50 ml. of benzene or toluene and raise the temperature for refluxing and azeotroping. About 17 ml. of water should be collected.

Add one part of this reaction product to 5 parts of thiobenzene and heat to 40 C. for 30 minutes, and then dilute to 50% ethanol.

Example 3 To 88 grams of 2-butene-l,4-diol add 0.43 ml. of copper acetate stock solution. Using a standard reflux apparatus weigh into the flask 232 grams of pentaethylene hexylamine. Raise the temperature to about C. and hold for about one hour, then allow the mixture to cool. Add 50 ml. of benzene or toluene and raise the temperature for refluxing and azeotroping. About 17 ml. of water should be collected.

Add one part of thiobenzene to 5 parts of this reaction product and heat to 140 C. for 5 minutes, then cool and dilute to 5 0% with ethanol.

Example 4 To 88 grams of 2-butene-l,4-diol add 0.43 ml. of copper acetate stock solution. Using a standard reflux apparatus weigh into the flask 189 grams of tetraethylene To 87 grams of 2-butyne-1,4-diol add 0.86 ml. of copper acetate stock solution. Using a standard reflux apparatus weigh into the flask 232 grams of pent'aethylene hexylamine.

Add one part of this reaction product to two parts of thiobenzene and heat to 120 C. for minutes, then dilute to 50% with ethanol;

Example 6 To 87 grams of 2-butyne-1,4-diol add 0.17 ml. of 0.5% aqueous solution of CoCl -6H O. Using a standard reflux apparatus weigh into the flask 60 grams of ethylene diamine. Raise the temperature to about 135 C. and hold for about one hour, then allow the mixture to cool. Add 50 ml. of benzene or toluene and raise the temperature for refluxing and azeotroping. About 17 ml. of water should be collected.

Add one part of this reaction product to two parts of thiobenzene and heat to 140 C. for 5 minutes. Cool and dilute to 50% with ethanol.

Example 7 To 88 grams of 2-butene-l,4-diol add 0.09 ml. of 0.5 aqueous solution of TiCl Using a standard reflux apparatus weigh into the flask 60 grams of ethylene diamine. Raise the temperature to about 135 C. and hold for about One hour, then allow the mixture to cool. Add 50 ml. of benzene or toluene and raise the temperature for refluxing and azeotroping. About 17 ml. of water should be collected.

Add one part of thiobenzene to two parts of this reaction product and heat to 120 C. for 10 minutes. Dilute to 50% with ethanol.

Example 8 To 87 grams of 2-butyne-1,4-diol add 0.09 ml. of a 0.5% aqueous solution of SnCl -2H O. Using a standard reflux apparatus weigh into the flask 232 grams of pentaethylene hexylamine. Raise the temperature to about 150 C. and hold for about one hour, then allow the mixture to cool. Add 50 ml. of benzene or toluene and raise the temperature for refluxing and azeot roping. About 17 ml. of water should be collected.

Add one part of thiobenzene to one part of this reaction product and heat to 100 C. for minutes. Dilute to 50% with ethanol.

Example 9 To 88 grams of 2-butene-l,4-diol add 0.43 ml. of a 0.5% aqueous solution of MnCl -4H O. Using a standard reflux apparatus Weigh into the flask 189 grams of tetraethylene pentamine. Raise the temperature to about 145 C. and hold for about one hour, then allow the mixture to cool. Add 50 ml. of benzene or toluene and raise the temperature for refluxing and azeotroping. About 17 ml. of water should be collected.

Add one part of thiobenzene to 5 parts of this reaction product and heat to 120 C. for 15 minutes. Dilute to 50% with ethanol.

Example 10 To 87 grams of 2-butyne-1,4-diol add 1.7 ml. of copper acetate stock solution. Using a standard reflux apparatus weigh into the flask 302 grams of pcntapropylene hexyl-amine. Raise the temperature to about 150 C. and hold for about one hour, then allow the mixture to cool. Add 50 ml. of benzene or toluene and raise the tempera- 6 ture for refluxing and azeotropiug. About 17 ml. of water should be collected.

Add one part of this reaction product to 5 parts of thiobenzene and heat to 120 C. for 15 minutes. Dilute to 50% with ethanol.

Example 11 The following tests were run to illustrate the effectiveness of the corrosion inhibiting compositions of this invention.

A synthetic water solution of the following properties was formulated:

Chloride (as sodium chloride), p.p.m. Total hardness, p.p.m. 150 pH 5.7 Alkalinity on the M scale This water was then saturated with CO at atmospheric pressure and ambient temperature. Bottles were filled /3 with this liquid containing varying quantities of different specific compositions and 10-20 mild carbon steel coupons were weighed and one inserted in each bottle. The vapor spaces were then filled with C0 The bottles were mounted on a wheel device which rotates slowly to allow the steel coupons to be exposed alternately to the liquid and gas phases.

These tests were run for one hour at 300 F. and for 23 additional hours at 250 F.

The percent protection was calculated by the formula:

where The dehydration-condensation reaction product was prepared in accordance with Example 1, and is identified in the table below as Reaction Product. The ratios of reaction product to thiobenzene and the parts per million of total composition varied as indicated in the table.

TABLE Percent Protection Inhibitor 10 p.p.m., 25 p.p.m., 100 p.p.m.,

percent percent percent:

Reaction Product 1 part Thioheuzene, 1 part 88 81 36 m-Nitroauiline 0 0 5 p.p.m., 15 p.p.m., 25 p.p.m., percent percent percent Reaction Product 5 parts Thiobenzcne, 1 part; l Reaction Product, 2 parts P ghiolgenzripe, 1 part G4 G8 eac ion roduct, 1 art Thiobeuzcue, 2 parts?" l 66 68 l 67 Reaction Product, 1 par Thiobenzene, 5 parts 61 1 65 Examples 12-20 Compositions prepared in accordance with Examples 2-5 and 8-10 provide protection of 60% or better when tested in accordance with the test method of Example 11 in concentrations of 10 p.p.m. Compositions prepared as per Examples 6 and 7, being prepared with lower molecular weight amines, will require higher concentrations in the order of 25-30 p.p.m. to provide 60% or better protection.

The following claims define the subject matter comprising the present invention, it being, of course, understood that equivalents known to those in the art are to be construed as within the scope and purview of the claims.

We claim:

1. A composition formed by: mixing one part of thiobenzene with from one to five parts of the dehydrationcondensation reaction product of an unsaturated diol of the formula wherein R is selected from the group consisting of hydrogen, methyl, and ethyl, and x is selected from the group consisting of CEC and -CH=CH- and an approximately equimolar quantity of a polyalkylene polyamine of the formula wherein R is a radical selected from the group consisting of ethylene and propylene and y is an integer from 1 to 4, inclusive; and heating the mixture to a temperature of about 40-140" C. and maintaining the temperature for about 5-30 minutes.

2. The composition of claim 1 in which the dehydration-condensation reaction product is formed from 2- butyne-1,4-diol and tetraethylene pentamine.

3. The composition of claim 1 in which the dehydration-condensation reaction product is formed from 2- butyne-1,4-diol and pentaethylene hexylamine.

4. The method of preparing a corrosion-inhibiting composition comprising the steps of (a) Reacting approximately equimolar quantities of 2- butyne-1,4-dio1 and tetraethylene pentamine in the presence of a small amount of a compound affording a chelate-forming metal ion, the amount of said metal compound being sulficient to cause an exothermic reaction between the unsaturated diol and the polyalkylene polyamine and to cause the formation of about one mole of water;

(b) Mixing one part of said reaction product of step (a) with from /5 to 5 parts by weight of thiobenzene; and then (c) Heating the mixture of step (b) to a temperature of about 40-140" C. and maintaining said temperature for 5-30 minutes.

5. The method of preparing a corrosion-inhibiting composition comprising the steps of (a) Reacting approximately equimolar quantities of 2-butyne-1,4-diol and tetraethylene pentamine in the presence of a small amount of a compound affording a chelate-forming metal ion, the amount of said metal compound being sufficient to cause an exothermic reaction between the unsaturated diol and the polyalkylene polyamine and to cause the formation of about one mole of Water;

(b) Mixing one part of said reaction product of step (a) with from /2 to 2 parts by weight of thiobenzene; and then (c) Heating the mixture of step (b) to a temperature of about 100-130 C. and maintaining said tempera ture for 10-20 minutes.

6. The method of claim wherein the composition is prepared from approximately equal quantities (by Weight) of said dehydration-condensation reaction product and said thiobenzene.

7. The method of preparing a corrosion-inhibiting composition comprising the steps of (a) Reacting approximately equimolar quantities of 2- butyne-1,4-diol and tetraethylene pentamine in the presence of a small amount of a compound affording a chelate-forming metal ion, the amount of said metal compound being sufficient to cause an exothermic reaction between the unsaturated diol and the polyalkylene polyamine and to cause the formation of about one mole of water;

(b) Mixing one part of said reaction product of step (a) with one part by weight of thiobenzene; and then (c) Heating the mixture of step (b) to a temperature of about 40-140 C. and maintaining said temperature for 5-30 minutes.

-8. The method of claim 7 wherein step (c) is carried out at about -130 C. for about 10-20 minutes.

9. The method of preparing a corrosion-inhibiting composition comprising the steps of (a) Reacting approximately equimolar quantities of 2- butyne-l,4-diol and pentaethylene hexylamine in the presence of a small amount of a compound aifording a chelate-forming metal ion, the amount of said metal compound being sufficient to cause an exothermic reaction between the unsaturated diol and the polyalkylene polyamine and to cause the formation of about one mole of water;

(b) Mixing one part of said reaction product of step (a) with one part by weight of thiobenzene; and then (0) Heating the mixture of step (b) to a temperature of about 40-140 C. and maintaining said temperature for 5-30 minutes.

10. The method of claim 9 wherein step (c) is carried out at about 110-130 C. for about 10-20 minutes.

11. The method of preparing a corrosion-inhibiting composition comprising the steps of:

(a) Adding about 1 mole of tetraethylene pentamine to about 1 mole of 2 butyne 1,4 diol containing from about 5-100 parts of copper acetate per million parts of diol; raising the temperature to initiate an exothermic reaction and tocause the formation of by-product water of reaction;

(b) Adding one part of thiobenzene to from /2 to 2 parts of the reaction product of step (a); and then (0) Heating the mixture of step (b) to a temperature of about 110-130 C. and maintaining the temperature for about 10-20 minutes.

12. The method of preparing a corrosion-inhibiting composition comprising the steps of:

(a) Adding about 1 mole of pentaethylene hexylamine to about 1 mole of 2 butyne 1,4 diol containing from about 5-100 parts of copper acetate per million parts of diol; raising the temperature to initiate an exothermic reaction and to cause the formation of by-product water of reaction;

(b) Adding one part of thiobenzene to from /2 to 2 parts of the reaction product of step (a); and then (c) Heating the mixture of step (b) to a temperature of about 110-130 C. and maintaining the temperature for about 10-20 minutes.

References Cited by the Examiner UNITED STATES PATENTS 2,845,393 7/1958 Varvel 252391 2,851,426 9/1958 Hughes 252391 2,932,622 4/1960 Bloch 260-48 3,029,286 4/1962 Bressler et al. 260584 3,044,864- 7/ 1962 Ryder 4463 3,065,283 11/1962t Happel et al 4463 X 3,098,097 7/1963 Grob et al. 260-584 CHARLES B. PARKER, Primary Examiner.

J. GREENWALD, JOSEPH P. BRUST, Examiners.

M. WEINBLATT, RICHARD L. RAYMOND,

Assistant Examiners. 

1. A COMPOSITION FORMED BY: MIXING ONE PART OF THIOBENZENE WITH FROM ONE TO FIVE PARTS OF THE DEHYDRATIONCONDENSATION REACTION PRODUCT OF AN UNSATURATED DIOL OF THE FORMULA 